Enhancing perception of frequency-lowered speech

ABSTRACT

Among other things, a sound processing device system is disclosed to assist a hearing-impaired human listener recognize speech sounds or phonemes. The device system may be configured at least to generate an output audio signal at least by transposing and causing a negative rank ordering of frequency of at least a portion of the input audio signal. Compression also may be performed on the at least the portion of the input audio signal as part of generating the output audio signal. The negative rank ordering may be performed on a high-frequency portion of the input audio signal that becomes a low-frequency portion of the output audio signal by the transposing. The low-frequency portion of the output audio signal may represent an inverted ordering of frequencies or frequency segments present in the high-frequency portion of the input audio signal.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.61/653,599, filed May 31, 2012, the entire disclosure of which,including its appendix, is hereby incorporated herein by reference.

STATEMENT OF GOVERNMENT INTEREST

This invention was made with government support under Grant No.DC010601/189K453 awarded by the National Institutes of Health. Thegovernment has certain rights in the invention.

TECHNICAL FIELD

Some embodiments of this invention pertain to a hearing aid device ordevice system that performs negative rank ordering of frequency of aninput audio signal, which, among other things, improves recognition ofsibilant fricatives over conventional techniques.

BACKGROUND

A variety of conventional techniques for assisting those withhigh-frequency hearing loss involve lowering high-frequency speechinformation into lower-frequency regions. Common to all these techniquesis a positive rank scaling of frequency, such that the ordering, fromlowest to highest, of frequency components in the higher frequencyregion of the input that is to be moved to the lower-frequency region ismaintained in the output (after lowering into the lower-frequencyregion).

For example, FIG. 1 illustrates some of these conventional techniquesinvolving positive rank scaling. In particular, FIG. 1( a) illustratesan example frequency range 101 of sound, a high-frequency region 104,which is illustrated as inaudible to a theoretical hearing-impairedperson, and a low-frequency region 102, which is illustrated as audibleto the theoretical hearing-impaired person.

FIGS. 1( b)-(e) illustrate conventional techniques for assisting thehearing-impaired person hear the high-frequency inaudible region 104 byshifting sounds within the high-frequency inaudible region 104 to thelower-frequency audible region 102. In this regard, it can be seen inFIG. 1 that in principle none of these techniques produce sound withinthe inaudible region 104 and, consequently, each of these techniques isillustrated within the audible region 102. In addition, each of thesetechniques involves positive rank scaling, as discussed below.

To elaborate, FIG. 1( b) illustrates a conventional linear frequencycompression technique 106. This technique searches for sound within thehigh-frequency inaudible region 104. If sound is detected within thehigh-frequency inaudible region 104, such as during time period 106 b,the entire frequency range 101 is linearly compressed so that it fitswithin the lower frequency audible region 102. This linear compressionis illustrated in FIG. 1( b) with the uniform zigzag line 107, which hasconsistent internal angles. Such linear compression exhibits positiverank scaling by maintaining, in the post-compression output, theordering of the frequencies present in the input sound pre-compression.When the hearing aid device does not detect sound within thehigh-frequency inaudible region 104, no compression of the input soundoccurs, such as during time periods 106 a and 106 c.

FIG. 1( c) illustrates a conventional linear frequency transpositiontechnique 108. This technique continually searches for an intensespectral peak in a limited frequency range called a “source region.”This “source region” is within the inaudible region 104. When an intensespectral peak is detected within the “source region”, a frequency rangeincluding the intense spectral peak is transposed one octave below intothe audible region 102 as illustrated by the transposed regions 108 a-c.Each of these transposed regions 108 a-c exhibits positive rank scaling,in that the ordered relationship between frequencies in the transposedinput sound is maintained in the transposed regions of the output sound.

FIG. 1( d) illustrates a conventional spectral feature translationtechnique 110. This technique searches for spectral features in thehigh-frequency inaudible region 104 that are characteristic of speech.If it is detected that there is a likelihood that speech informationexists in the high-frequency inaudible region 104, such as during timeperiod 110 b, a frequency range including the suspected high-frequencyspeech information is transposed or translated on an octave scale intothe lower-frequency audible range 102. This translated frequency rangeis illustrated in FIG. 1( d) with the box 110 d and exhibits positiverank scaling, in that the ordered relationship between frequencies inthe transposed input sound is maintained in the transposed region of theoutput sound. If it is detected that there is not a likelihood thatspeech information exists in the high-frequency inaudible region 104,such as during time periods 110 a and 110 c, no translation of the inputsound occurs.

FIG. 1( e) illustrates a conventional nonlinear frequency compressiontechnique. This technique compresses frequencies above a start frequency112 a non-linearly over time to emphasize certain frequencies or ranges,while maintaining positive rank scaling in the compressed region. Thisnon-linear compression is illustrated by the non-uniform zigzag lineshaving differing internal angles shown in FIG. 1( e), one of which iscalled out as reference 112 b. The frequencies below the start frequency112 a are not compressed.

While the conventional techniques of FIG. 1, and other conventionaltechniques involving positive rank scaling in shifted frequencies,assist hearing-impaired individuals in hearing otherwise inaudiblesounds, there is a need in the art for further improvement of hearingaid devices.

SUMMARY

At least the above-described problems are addressed and technicalsolutions are achieved in the art at least by a sound processing devicesystem configured to assist a hearing-impaired human listener recognizesounds according to various embodiments of the present invention. Thesound processing device system may include a memory device system; and adata processing device system communicatively connected to the memorydevice system. The data processing device system may be configured by aprogram stored in the memory device system at least to receive an inputaudio signal; and generate an output audio signal at least bytransposing and causing a negative rank ordering of frequency of atleast a portion of the input audio signal.

In some embodiments of the present invention, the data processing devicesystem is configured by the program at least to generate an output audiosignal at least by transposing and causing a negative rank ordering of ahigh-frequency portion of the input audio signal, the high frequencyportion of the input audio signal becoming a low-frequency portion ofthe output audio signal. The low-frequency portion of the output audiosignal may represent an inverted ordering of frequencies present in thehigh-frequency portion of the input audio signal.

In some embodiments, the negative rank ordering includes an inversion ofan ordering of frequencies present in the at least the portion of theinput audio signal.

In some embodiments, the sound processing device system further includesa sound receiving device system and a sound producing device system. Thesound receiving device system may be communicatively connected to thedata processing device system and may be configured to receive sound andgenerate the input audio signal. The sound producing device system maybe communicatively connected to the data processing device system andmay be configured to produce sound based upon the output audio signal.

In some embodiments, the negative rank ordering includes frequencyinverting and compressing the at least the portion of the input audiosignal.

In some embodiments, the input audio signal is a first portion of aninput audio signal stream, and the output audio signal is a firstportion of an output audio signal stream. In this regard, the dataprocessing device system may be further configured by the program atleast to (a) identify a speech pattern present in the first portion ofthe input audio signal stream; (b) generate, in response to the speechpattern being identified as present in the first portion of the inputaudio signal stream, the first portion of the output audio signal streamat least by inverting a frequency relationship of at least part of thefirst portion of the input audio signal stream; (c) identify that thespeech pattern is not present in a second portion of the input audiosignal stream that is other than the first portion of the input audiosignal stream; and (d) generate, in response to identifying that thespeech pattern is not present in the second portion of the input audiosignal stream, a second portion of the output audio signal streamwithout inverting the frequency relationship of at least part of thesecond portion of the input audio signal stream, the second portion ofthe output audio signal stream being other than the first portion of theoutput audio signal stream. The speech pattern may be frication.

In some embodiments, the data processing device system is furtherconfigured by the program at least to: (e) identify that the firstportion of the input audio signal stream exhibits higher energy at ahigh-frequency range as compared to a mid-frequency range of the firstportion of the input audio signal stream; and (f) cause, by way of atleast a gain, an attenuation, or both a gain and an attenuation, and inresponse to identifying that the first portion of the input audio signalstream exhibits the higher energy at the high-frequency range, alow-frequency range of the first portion of the output audio signalstream to be relatively emphasized or de-emphasized as compared toanother frequency range of the first portion of the output audio signalstream or another time segment of the output audio signal stream togenerate a perceptual cue to facilitate distinguishing of similarsounds, the low-frequency range of the first portion of the output audiosignal stream corresponding, prior to the inverting the frequencyrelationship of the first portion of the input audio signal stream, tothe high-frequency range of the first portion of the input audio signalstream.

In some embodiments, the data processing device system is furtherconfigured by the program at least to: (g) identify a speech patternpresent in a third portion of the input audio signal stream that isother than the first portion of the input audio signal stream and thesecond portion of the input audio signal stream; (h) generate, inresponse to the speech pattern being identified as present in the thirdportion of the input audio signal stream, a third portion of the outputaudio signal stream at least by inverting a frequency relationship ofthe third portion of the input audio signal stream, the third portion ofthe output audio signal stream being other than the first portion of theoutput audio signal stream and the second portion of the output audiosignal stream; (i) identify that the third portion of the input audiosignal stream exhibits higher energy at a mid-frequency range ascompared to a high-frequency range of the third portion of the inputaudio signal stream; and (j) output the third portion of the outputaudio signal stream without causing, by way of at least a gain, anattenuation, or both a gain and an attenuation, a low-frequency range ofthe third portion of the output audio signal stream to be relativelyemphasized or de-emphasized as compared to another frequency range ofthe third portion of the output audio signal stream or another timesegment of the output audio signal stream, the low-frequency range ofthe third portion of the output audio signal stream corresponding, priorto the inverting the frequency relationship of the third portion of theinput audio signal stream, to the high-frequency range of the thirdportion of the input audio signal stream.

In some embodiments, the data processing device system is furtherconfigured by the program at least to: (a) determine whether or not theinput audio signal exhibits higher energy at a high-frequency range thanat a mid-frequency range of the input audio signal; and (b) cause, byway of at least a gain, an attenuation, or both a gain and anattenuation, and in response to determining that the input audio signalexhibits the higher energy at the high-frequency range, a low-frequencyrange of the output audio signal to be relatively emphasized orde-emphasized as compared to another frequency range or another timesegment of the output audio signal to generate a perceptual cue tofacilitate distinguishing of similar sounds, the low-frequency range ofthe output audio signal corresponding, prior to the transposing andnegative rank ordering of the input audio signal, to the high-frequencyrange of the input audio signal.

In some embodiments, the data processing device system is furtherconfigured by the program at least to (a) determine whether or not theoutput audio signal exhibits higher energy at a low-frequency range thanat a mid-frequency range of the output audio signal; and (b) cause, byway of at least a gain, an attenuation, or both a gain and anattenuation, and in response to determining that the input audio signalexhibits the higher energy at the high-frequency range, thelow-frequency range of the output audio signal to be relativelyemphasized or de-emphasized as compared to another frequency range oranother time segment of the output audio signal to generate a perceptualcue to facilitate distinguishing of similar sounds, the low-frequencyrange of the output audio signal corresponding, prior to the transposingand negative rank ordering of the input audio signal, to thehigh-frequency range of the input audio signal.

In some embodiments, a sound processing device system is configured toassist a hearing-impaired human listener recognize sounds, the soundprocessing device system including a memory device system and a dataprocessing device system communicatively connected to the memory devicesystem. In at least some of these embodiments, the data processingdevice system is configured by a program stored in the memory devicesystem at least to: (1) receive an input audio signal; (2) generate anoutput audio signal based at least upon a processing of the input audiosignal; and (3) determine that (a) the input audio signal exhibitshigher energy at a high-frequency range as compared to a mid-frequencyrange of the input audio signal, or (b) the output audio signal exhibitshigher energy at a low-frequency range as compared to a mid-frequencyrange of the output audio signal, wherein, in response to determining(a) or (b), the data processing device system is configured by theprogram at least to cause the output audio signal to include aperceptual cue at least by including an emphasis or a de-emphasis of thelow-frequency range of the output audio signal as compared to anotherfrequency range or another time segment of the output audio signal atleast by an application of a gain, an attenuation, or both a gain and anattenuation, the perceptual cue being caused to be included regardlessof frequency regions where hearing loss is occurring for thehearing-impaired human listener.

In this regard, the sound processing device may include a soundreceiving device system communicatively connected to the data processingdevice system and configured to receive sound and generate the inputaudio signal; and a sound producing device system communicativelyconnected to the data processing device system and configured to producesound based upon the output audio signal.

The processing of the input audio signal may include transposing andcausing a negative rank ordering of frequency of at least a portion ofthe input audio signal. The negative rank ordering may include aninversion of an ordering of frequencies present in the at least theportion of the input audio signal.

The processing of the input audio signal may include frequency invertingand compressing at least the portion of the input audio signal.

The processing of the input audio signal may include transposing andcausing a negative rank ordering of the high-frequency portion of theinput audio signal, the high frequency portion of the input audio signalbecoming the low-frequency portion of the output audio signal.

The input audio signal may be a first portion of an input audio signalstream, the output audio signal may be a first portion of an outputaudio signal stream, and the data processing device system may befurther configured by the program at least to: (4) identify a speechpattern present in the first portion of the input audio signal stream;(5) generate, in response to the speech pattern being identified aspresent in the first portion of the input audio signal stream, the firstportion of the output audio signal stream at least by transposing andcausing a negative rank ordering of frequency of at least part of thefirst portion of the input audio signal stream; (6) identify that thespeech pattern is not present in a second portion of the input audiosignal stream that is other than the first portion of the input audiosignal stream; and (7) generate, in response to identifying that thespeech pattern is not present in the second portion of the input audiosignal stream, a second portion of the output audio signal streamwithout inverting a frequency relationship of at least part of thesecond portion of the input audio signal stream, the second portion ofthe output audio signal stream being other than the first portion of theoutput audio signal stream.

In some embodiments, a hearing aid device system includes a soundreceiving device system, a sound producing device system, a memorydevice system, and a data processing device system. The sound receivingdevice system may be configured to receive sound and generate an inputaudio signal. The sound producing device system may be configured toproduce sound based upon an output audio signal. The data processingdevice system may be communicatively connected to the memory devicesystem, the sound receiving device system, and the sound producingdevice system, and the data processing device system may be configuredby a program stored in the memory device system at least to: (i) receivethe input audio signal; (ii) identify a speech pattern present in theinput audio signal; (iii) generate, in response to the speech patternbeing identified as present in the input audio signal, the output audiosignal at least by transposing and causing a negative rank scaling offrequency of at least a portion of the input audio signal; (iv) identifythat the input audio signal exhibits higher energy at a high-frequencyrange as compared to a mid-frequency range of the input audio signal;and (v) cause, by way of at least a gain, an attenuation, or both a gainand an attenuation, and in response to determining that the input audiosignal exhibits the higher energy at the high-frequency range, alow-frequency range of the output audio signal to be relativelyemphasized or de-emphasized as compared to another frequency range oranother time segment of the output audio signal to generate a perceptualcue to facilitate distinguishing of similar sounds, the low-frequencyrange of the output audio signal corresponding, prior to the transposingand causing the negative rank scaling of frequency of the input audiosignal, to the high-frequency range of the input audio signal.

The features of each of the embodiments described above may be combinedin any possible permutation in other respective embodiments of thepresent invention. In addition, the systems, according to theembodiments described above, may be implemented as respective methods oras respective one or more computer-readable mediums storing one or morecomputer-executable programs comprising computer-executable instructionsconfigured to execute such methods. The above-discussed memory devicesystems and computer-readable mediums are one or more non-transitorycomputer-readable memories or mediums, according to at least someembodiments of the present invention.

In addition to the embodiments described above, further embodiments willbecome apparent by reference to the drawings and by study of thefollowing detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more readily understood from the detaileddescription of embodiments presented below considered in conjunctionwith the attached drawings, of which:

FIG. 1 illustrates some conventional techniques for compensating for anindividual's high-frequency hearing loss;

FIG. 2 illustrates a relationship between spectral peak frequency andperception of /s/, according to some embodiments of the presentinvention;

FIG. 3 illustrates an example frequency I/O relationship that preserves/s/ and /∫/ discrimination after lowering the input frequency withnegative rank ordering or scaling, according to some embodiments of thepresent invention;

FIG. 4 illustrates example output of an implementation involvingnegative rank ordering or scaling of frequency, according to someembodiments of the present invention;

FIG. 5 illustrates an example hardware configuration of a soundprocessing device system 500 configured to assist a hearing-impairedhuman listener recognize sounds at least by implementing negative rankordering or scaling of frequency, according to some embodiments of thepresent invention.

FIG. 6 illustrates a hearing aid device configured to fit within a humanear, according to some embodiments of the present invention;

FIG. 7 illustrates a method for performing negative rank ordering orscaling of frequency on an input audio signal, according to someembodiments of the present invention;

FIGS. 8-10 illustrate negative rank ordering or scaling of frequency I/Ofunctions, according to some embodiments of the present invention; and

FIGS. 11-18 pertain to comparative examples between embodiments of thepresent invention and conventional techniques.

It is to be understood that the attached drawings are for purposes ofillustrating the concepts of the invention and may not be to scale.

DETAILED DESCRIPTION

The inventor notes that a shortcoming of the conventional techniques ofFIG. 1, and other conventional techniques involving positive rankscaling in shifted frequencies, is an increase in confusion between thesibilant fricatives (/s/ and /∫/ or “sh”). In particular,frequency-lowered /s/ is more often perceived as /∫/, which naturallyhas a lower spectral peak. Data gathered under the direction of theinventor has revealed an unexpected relationship between thefrequency-lowered spectral peak and perception: a nonmonotonicrelationship exists such that perception of /s/ returns when spectralpeaks are very low in frequency. See, e.g., FIG. 2, which illustrates arelationship between spectral peak frequency and perception of /s/.

Some embodiments of the present invention utilize this relationship bygenerating an output audio signal at least by transposing (e.g., bylowering in frequency) and causing a negative rank ordering or scalingof at least a portion (e.g., one or more frequency ranges, one or moretime segments, or both) of the input audio signal. In some embodiments,this negative rank ordering or scaling is implemented as a reciprocalfunction of frequency at least in a frequency band of interest, where atleast the frequency band is inverted so that what is very high infrequency at the input becomes very low in frequency at the output, andwhat is toward the middle of the spectrum on the input stays toward themiddle of the spectrum at the output (e.g., closer to its natural placeof origin). See, e.g., FIG. 3, which illustrates an example frequencyI/O relationship that preserves /s/ and /∫/ discrimination afterlowering the input frequency with negative rank ordering or scaling,according to some embodiments of the present invention.

With respect to FIG. 3, the natural productions of /s/ across talkersand articulatory contexts have peak energy between 4 and 10 kHz (e.g.,the input region denoted by reference numerals 301 and 302) and naturalproductions of /∫/ have peak energy between 2 and 5 kHz (e.g., the inputregions denoted by reference numerals 303 and 304, as well as someoverlap (not shown in FIG. 3) with regions 301 and 302 between 4 and 5kHz on the input side). At higher output frequencies (e.g., >500 Hzrepresented by regions 301 and 304), peak energy will more likely beperceived as /∫/. In this regard, reference numeral 301 represents aregion where a frequency-lowered (e.g., by way of negative rank orderingor scaling of frequency) /s/ would likely be perceived as /∫/. At thelowest output frequencies (e.g., <500 Hz represented by regions 302 and303), peak energy will more likely be perceived as /s/. In this regard,reference numeral 303 represents a region where a frequency-lowered /∫/would likely be perceived as /s/. In order to have a natural productionof /s/ be perceived as such after frequency lowering, according to someembodiments, the frequency I/O function (black dotted line in FIG. 3)falls within the region 302, and falls within the region 304 for /∫/.

FIG. 4 illustrates example output 404 of an implementation involvingnegative rank scaling of frequency, according to some embodiments of thepresent invention. In this regard, FIG. 4 illustrates a non-limitingexample where negative rank scaling of frequency is applied to an inputaudio signal during time period 404 b. The negative rank scaling appliedduring time period 404 b, according to these embodiments, inverts inputaudio signal frequencies or a frequency relationship thereof within thehigher-frequency inaudible region 401 and transposes, shifts, ortranslates them to the lower-frequency audible region 402. Accordingly,a highest frequency 406 within the inaudible region 401 becomes thelowest frequency 408 within the audible region 402, and a low frequency410 in the inaudible region 401 (which actually is a middle frequency inthe spectrum 403) shifts a small amount to become a frequency 407 withinthe audible region 402 (and remains a middle frequency in the spectrum403).

Some embodiments implementing negative rank ordering or scaling offrequency, such as that shown in FIG. 4, may include a timing component,where the negative rank ordering or scaling is selectively applied overtime, depending upon characteristics of the input audio signal. Examplesof such characteristics will be described in greater detail below withrespect to FIG. 7 (e.g., block 704). In the example embodiments of FIG.4, negative rank ordering or scaling is not applied during time periods404 a and 404 c, whereas negative rank ordering or scaling is appliedduring time period 404 b, based on an analysis of characteristics of theinput audio signal.

Some embodiments implementing negative rank ordering, such as that shownin FIG. 4, may include frequency compression, such as non-linearcompression. In this regard, the phrase, “negative rank scaling” may beused to indicate negative rank ordering of frequencies that involvesfrequency compression. On the other hand, the phrase “negative rankordering” should not be interpreted to exclude the possibility offrequency compression. The example embodiments of FIG. 4 illustratenon-linear compression with the non-uniform zigzag line 404 d havingdiffering internal angles. The compression applied may vary based on ahuman-listener's personal characteristics, and further details andexamples of such compression with respect to some embodiments of thepresent invention are provided with respect to FIGS. 8 and 9, discussedbelow. In some embodiments, the compression may be provided by sine waveoscillators that synthesize frequencies lowered by a negative rankordering process according to an embodiment of the present inventionfollowing signal analysis via Fast Fourier Transform.

The formation of the output audio signal by way of a negative rankscaling of frequency, according to at least one embodiment of thepresent invention, has been demonstrated to improve recognition of, notonly of /s/ and /∫/, but also for other phonemes, including /t/, /k/,/z/, /d₃/ (“j”), /t∫/ (“ch”), and /j/ (“y”), as compared to conventionalpositive rank scaling techniques.

FIG. 5 illustrates an example hardware configuration of a soundprocessing system 500 configured to assist a hearing-impaired humanlistener recognize sounds at least by implementing negative rankordering or scaling of frequency, according to some embodiments of thepresent invention.

It is noted that reference throughout this specification to “oneembodiment” or “an embodiment” or “an example embodiment” or “anillustrated embodiment” or “a particular embodiment” and the like meansthat a particular feature, structure or characteristic described inconnection with the embodiment is included in at least one embodiment.Thus, the appearances of the phrases “in one embodiment” or “in anembodiment” or “in an example embodiment” or “in this illustratedembodiment” or “in this particular embodiment” and the like in variousplaces throughout this specification are not necessarily all referringto one embodiment or a same embodiment. Furthermore, the particularfeatures, structures, or characteristics of different embodiments may becombined in any suitable manner to form one or more other embodiments.

It additionally is noted that, unless otherwise explicitly stated orrequired by context, the word “or” is used in this disclosure in anon-exclusive sense. Further, unless otherwise explicitly noted orrequired by context, the word “set” is intended to mean one or more, andthe word “subset” is intended to mean a set having the same or fewerelements of those present in the subset's parent or superset.

Further, the phrase “at least” is used herein to emphasize thepossibility that other elements can exist besides those explicitlylisted. However, unless otherwise explicitly noted (such as by the useof the term “only”) or required by context, non-usage herein of thephrase “at least” includes the possibility that other elements existbesides those explicitly listed. For example, the phrase, ‘based atleast upon A’ includes A, as well as one or more other additionalelements besides A. In the same manner, the phrase, ‘based upon A”includes A, as well as one or more other additional elements besides A.However, the phrase, ‘based only upon A’ includes only A.

The term “program” in this disclosure should be interpreted as a set ofinstructions or modules that can be executed by one or more componentsin a system, such as a controller system or data processing devicesystem, in order to cause the system to perform one or more operations.The set of instructions or modules can be stored by any kind of memorydevice, such as those described subsequently with respect to the memorydevice system 530 shown in FIG. 5. In addition, this disclosure maydescribe that the instructions or modules of a program are configured tocause the performance of an action. The phrase “configured to” in thiscontext is intended to include at least (a) instructions or modules thatare presently in a form executable by one or more data processingdevices to cause performance of the action (e.g., in the case where theinstructions or modules are in a compiled and unencrypted form ready forexecution), and (b) instructions or modules that are presently in a formnot executable by the one or more data processing devices, but could betranslated into the form executable by the one or more data processingdevices to cause performance of the action (e.g., in the case where theinstructions or modules are encrypted in a non-executable manner, butthrough performance of a decryption process, would be translated into aform ready for execution). The word “module” may be defined as a set ofinstructions.

The word “device” and the phrase “device system” both are intended toinclude one or more physical devices or sub-devices (e.g., pieces ofequipment) that interact to perform one or more functions, regardless ofwhether such devices or sub-devices are located within a same housing ordifferent housings. In this regard, the word “device”, may equivalentlybe referred to as a “device system”.

Further, the phrase “in response to” may be used in this disclosure. Forexample, this phrase might be used in the following context, where anevent A occurs in response to the occurrence of an event B. In thisregard, such phrase includes, for example, that at least the occurrenceof the event B causes or triggers the event A.

Returning to the particulars of FIG. 5, the system 500 may include adata processing device system 510, an input-output device system 520,and a processor-accessible memory device system 530. Theprocessor-accessible memory device system 530 and the input-outputdevice system 520 are communicatively connected to the data processingdevice system 510.

The data processing device system 510 includes one or more dataprocessing devices that implement or execute, in conjunction with otherdevices, such as those in the system 500, methods of various embodimentsof the present invention. Each of the phrases “data processing device”,“data processor”, “processor”, and “computer” is intended to include anydata processing device, such as a central processing unit (“CPU”), adesktop computer, a laptop computer, a mainframe computer, tabletcomputer, a personal digital assistant, a cellular (smart) phone, andany other device for processing data, managing data, or handling data,whether implemented with electrical, magnetic, optical, biologicalcomponents, or otherwise.

The memory device system 530 includes one or more processor-accessiblememory devices configured to store information, including theinformation needed to execute the methods of various embodiments. Thememory device system 530 may be a distributed processor-accessiblememory device system including multiple processor-accessible memorydevices communicatively connected to the data processing device system510 via a plurality of computers and/or devices. On the other hand, thememory device system 530 need not be a distributed processor-accessiblememory system and, consequently, may include one or moreprocessor-accessible memory devices located within a single dataprocessing device.

Each of the phrases “processor-accessible memory” and“processor-accessible memory device” is intended to include anyprocessor-accessible data storage device, whether volatile ornonvolatile, electronic, magnetic, optical, or otherwise, including butnot limited to, registers, floppy disks, hard disks, Compact Discs,DVDs, flash memories, ROMs, and RAMs. In some embodiments, each of thephrases “processor-accessible memory” and “processor-accessible memorydevice” is intended to include a non-transitory computer-readablestorage medium. And in some embodiments, the memory device system 530can be considered a non-transitory computer-readable storage mediumsystem.

The phrase “communicatively connected” is intended to include any typeof connection, whether wired or wireless, between devices, dataprocessors, or programs in which data may be communicated. Further, thephrase “communicatively connected” is intended to include a connectionbetween devices or programs within a single data processor, a connectionbetween devices or programs located in different data processors, and aconnection between devices not located in data processors at all. Inthis regard, although the memory device system 530 is shown separatelyfrom the data processing device system 510 and the input-output devicesystem 520, one skilled in the art will appreciate that the memorydevice system 530 may be located completely or partially within the dataprocessing device system 510 or the input-output device system 520.Further in this regard, although the input-output device system 520 isshown separately from the data processing device system 510 and thememory device system 230, one skilled in the art will appreciate thatsuch system may be located completely or partially within the dataprocessing system 510 or the memory device system 530, depending uponthe contents of the input-output device system 520. Further still, thedata processing device system 510, the input-output device system 520,and the memory device system 530 may be located entirely within the samedevice or housing or may be separately located, but communicativelyconnected, among different devices or housings. In the case where thedata processing device system 510, the input-output device system 520,and the memory device system 530 are located within the same device, thesystem 500 of FIG. 5 can be implemented by a single application-specificintegrated circuit (ASIC) in some embodiments.

The input-output device system 520 may include a microphone, a mouse, akeyboard, a touch screen, another computer, a processor-accessiblememory device, or any device or combination of devices from which adesired selection, desired information, instructions, sound, or anyother data is input to the data processing device system 510. Theinput-output device system 520 may include a user-activatable controlsystem that is responsive to a user action. The input-output devicesystem 520 may include any suitable interface for receiving information,instructions, or any data from other devices and systems described invarious ones of the embodiments of the present invention.

The input-output device system 520 also may include a speaker, a displaydevice system, a processor-accessible memory device, or any device orcombination of devices to which information, instructions, sound, or anyother data is output by the data processing device system 510. Theinput-output device system 220 may include any suitable interface foroutputting information, instructions, or data to other devices andsystems described in various ones of the embodiments.

If the input-output device system 520 includes a processor-accessiblememory device, such memory device may or may not form part or all of thememory device system 530.

In some embodiments, the system 500 is implemented as a hearing aiddevice 600 illustrated in FIG. 6 and configured to fit within an earcanal of a human ear. In this regard, the hearing aid device 600 may beconsidered a device system including multiple hardware components.According to some embodiments these hardware components may include asound receiving (and recording) device system 602 configured to receivesound from outside the human ear and generate a corresponding inputaudio signal. The sound receiving device system 602 may include one ormore microphones and any associated circuitry (e.g., ananalog-to-digital (“ADC”) converter) configured to generate the inputaudio signal from the received sound. In this regard, the soundreceiving device system 602 may be considered at least part of the datainput-output device system 520 in FIG. 5.

Although not required, the input audio signal from the sound receivingdevice system 602 may be subject to filtering or conditioning byfiltering/conditioning circuitry 604. Such filtering or conditioning mayinclude any preprocessing of the input audio signal to, for example,improve the signal-to-noise ratio (e.g., noise reduction preprocessing)of the input audio signal, provide gain to the input audio signal atleast in frequency ranges where the user is experiencing hearing loss,or any other preprocessing (e.g., gain adjustment, speech-in-noiseclassification, phoneme classification, known in the art) suitable forfacilitating the execution of negative rank ordering or scalingprocessing, according to various embodiments of the present invention,such as those described with respect to FIG. 7, below. Although thefiltering/conditioning circuitry 604 is shown separately from the one ormore processing devices 606 in FIG. 6, such circuitry may instead beimplemented by the one or more data processing devices 606, according tosome embodiments of the present invention. Alternatively, thefiltering/conditioning circuitry 604 may be considered at least part ofthe sound receiving device system 602 as circuitry associated with oneor more microphones and configured to generate the input audio signal.

The filtered/conditioned input audio signal from thefiltering/conditioning circuitry 604 may be stored in one or morenon-transitory memory devices 608 for accessing by the one or moreprocessing devices 606 as the one or more processing devices 606 analyzethe input audio signal and execute negative rank ordering or scaling offrequency under the direction of one or more control programs stored inthe one or more memory devices 608. Examples of the processing performedby the one or more processing devices 606 are provided at least withrespect to FIG. 7, discussed below. The filtering/conditioning circuitry604 and the one or more processing devices 606 may be considered part ofthe data processing device system 510 in FIG. 5, and the one or morememory device(s) 608 may be considered at least part of theprocessor-accessible memory device system 530 in FIG. 5.

A result of the one or more processing devices 606 processing the inputaudio signal, including selectively performing negative rank ordering orscaling of frequency, is the generation of an output audio signal thatis provided to a sound producing device system 610, which is configuredto produce output sound, based upon the output audio signal, towards theuser's ear drum that is better suited for speech recognition than theinput sound. The sound producing device system 610 may include one ormore speakers and associated circuitry (e.g., one or moredigital-to-analog (“DAC”) converters, amplifiers) configured to producethe output sound based upon the output audio signal from the one or moreprocessing devices 606. In this regard, the sound producing devicesystem 610 may be considered at least part of the data input-outputdevice system 520 in FIG. 5.

Although not shown in FIG. 6, one or more internal power sources for thehearing aid device 600 are included to provide power to each of thehardware components 602, 604, 606, 608, and 610. Similarly, with respectto FIG. 5, one or more power sources are included to provide power toeach of the hardware components 510, 520, and 530, although such one ormore power sources are not shown in FIG. 5.

FIG. 7 illustrates a method 700 for performing negative rank ordering orscaling of frequency on an input audio signal, according to someembodiments of the present invention. The method 700 may be executed bythe system 500 in FIG. 5 or the system 600 in FIG. 6 according to one ormore processor-executable programs stored in the processor-accessiblememory device system 530, 608 executed at least by the data processingdevice system 510, 606. Stated differently, at least the data processingdevice system 510, such as the one or more processing devices 606, maybe configured by one or more processor-executable programs stored in theprocessor-accessible memory device system 530, such as the one or morememory devices 608, to execute at least the method 700. Although themethod 700 may be implemented at least by the data processing devicesystem 510 or the one or more processing devices 606, the followingdescription of method 700 will refer to the data processing devicesystem 510 merely for ease of discussion. It should be noted, however,that the phrase “data processing device system 510” in the followingdescription of method 700 may equivalently be replaced with a referenceto the one or more data processing devices 606, according to someembodiments of the present invention. Further, the following discussionsoften describe characteristics of and operations performed on audiosignals, such as an input audio signal or an output audio signal. Inthis regard, it is noted that such characteristics are embodied, andthat such operations are performed on the respective audio signals in astate where the audio signals are embodied in a non-transitorycomputer-readable storage medium within the processor-accessible memorydevice system 530 or the one or more non-transitory memory devices 608.

At a fundamental level, according to some embodiments, the method 700includes the data processing device system 510 receiving an input audiosignal (e.g., according to program instructions associated with block702) and generating, at least in some cases or at some point in time, anoutput audio signal (e.g., according to program instructions associatedwith block 712 or 714) at least by transposing and causing a negativerank ordering or scaling of frequency (e.g., according to programinstructions associated with block 708) of at least a portion (e.g., oneor more frequency ranges, one or more time segments, or both) of theinput audio signal. In some embodiments, for example, the output audiosignal is generated at least by transposing and causing a negative rankordering or scaling of a high-frequency portion of the input audiosignal, the high-frequency portion of the input audio signal becoming alow-frequency portion of the output audio signal. In this regard, thelow-frequency portion of the output audio signal may represent aninverted ordering of frequencies present in the high-frequency portionof the input audio signal.

In some embodiments, the input audio signal received according toprogram instructions associated with block 702 may be the input audiosignal output directly from the sound receiving device system 602 inFIG. 6 or, in embodiments where the filtering/conditioning circuitry 604exists, may be the input audio signal as filtered or conditioned by thefiltering/conditioning circuitry 604.

In embodiments employing the method 700, the input audio signal may beanalyzed according to program instructions associated with block 704 todetermine if high frequency speech is present in the input audio signal.In some embodiments, block 704 employs a frication detector to detecthigh-frequency aperiodic noise associated with the fricative,affricative, and stop consonant sound classes. However, the invention isnot limited to any particular high-frequency speech detection, and anyother high-frequency speech detection technique known in the art may beused for block 704. For example, a spectral balance detector or a morecomplicated analysis of modulation frequency and depth or a combinationof parameters, or any other technique known in the art may beimplemented for block 704. In addition, it should be noted that theprocessing associated with block 704 need not be implemented by theprocessing device(s) 606 in FIG. 6 and instead may be implemented by thefiltering/conditioning circuitry 604, according to some embodiments ofthe present invention.

If a viable high-frequency speech pattern (e.g., frication) isidentified in the input audio signal at block 704, processing mayproceed at least to block 708 where negative rank ordering or scaling offrequency is performed on at least a portion (e.g., one or morefrequency ranges, one or more time segments, or both) of the input audiosignal. However, if a viable high-frequency speech pattern (e.g.,frication) is not identified in the input audio signal at block 704, theinput audio signal is passed through to the next stage of processing(e.g., the input audio signal may be merely passed through as the outputaudio signal to the sound producing device system 610 and FIG. 6) atblock 706 and no negative rank ordering or scaling of the input audiosignal is performed, according to some embodiments.

In this regard, the determination associated with block 704 may beconsidered a selector that continually analyzes the input audio signaland determines whether or not negative rank ordering or scaling offrequency is applied to various portions (e.g., frequency ranges, timesegments, or both) of the input audio signal. For example, assume thatthe input audio signal is considered an input audio signal stream thatis continually analyzed by the negative rank ordering or scalingselector of block 704, and the output audio signal generated by the dataprocessing device system 510 based upon the input audio signal stream isan output audio signal stream. In this case, if the negative rankordering or scaling selector of block 704 identifies a high-frequencyspeech pattern present in a first portion (e.g., one or more frequencyranges, one or more time segments, or both) of the input audio signalstream, the data processing device system 510 may generate, in responseto the high-frequency speech pattern being identified as present in thefirst portion of the input audio signal stream, a first portion of theoutput audio signal stream (e.g., time period 404 b of FIG. 4 andassociated frequency range, where reference 404 represents an exampleoutput audio signal stream) at least by inverting the frequency orderingof at least part of the first portion of the input audio signal streamaccording to negative rank ordering or scaling performed at block 708.On the other hand, if the negative rank ordering or scaling selector ofblock 704 does not identify a viable high-frequency speech patternpresent in a subsequent second portion (e.g., one or more frequencyranges, one or more time segments, or both) of the input audio signalstream, the data processing device system 510 may generate, in responseto identifying that the speech pattern is not present in the secondportion of the input audio signal stream, a subsequent second portion ofthe output audio signal stream (e.g., time period 404 c and associatedfrequency range of FIG. 4) without inverting the frequency ordering ofat least part of or any part of the second portion of the input audiosignal stream according to the negative rank ordering or scaling ofblock 708.

In one specific example embodiment, the detector of block 704 is aspectral balance detector configured to compare the energy above 2500 Hzto the energy below 2500 Hz in the input audio signal. In this regard,negative rank ordering or scaling (e.g., block 708) occurs when theformer is greater than the latter (i.e., the input is high-frequencydominated), which works well for speech in quiet. Analysis was carriedout over successive windows (e.g., input audio signal stream timeperiods or segments) that were 5.8 ms in duration (i.e., 128 points at a22,050-Hz sampling frequency). To prevent the switch of block 704 frombeing overly active, yet sensitive to rapid changes in high-frequencyenergy, there was a hysteresis to the switching behavior in thisembodiment. In particular, spectral balance was computed from a weightedhistory of four successive windows, with the most recent window giventhe greatest weight (i.e., 0.4) and the most distant window given theleast weight (i.e., 0.1). The reasoning is that if an intense, briefhigh-frequency sound (e.g., the ‘burst’ of energy associated with therelease of air following the silent interval for stop consonants) was topass through in the input audio signal, the switch of block 704 wouldtrigger and that window and the one or two windows immediately followingwould be lowered, depending on the input. If a brief high-frequencynoise sporadically occurred during a low-frequency dominated vowel, itmight not be enough to trigger the switch at block 704, thereby normalprocessing (e.g., through to block 706) would be maintained. It shouldbe noted, however, that the invention is not limited to the details ofthis embodiment, which is referred to for purposes of illustration only.Further, one or more aspects of this embodiment may be incorporated intoother embodiments of the present invention.

In some embodiments, if the data processing device system 510 determinesthat there is useful high-frequency speech present in the input audiosignal according to the instructions associated with block 704, the dataprocessing device system 510 performs negative rank ordering or scalingof frequency according to any one of the various embodiments of thepresent invention to at least a portion (e.g., one or more frequencyranges, one or more time segments, or both) of the input audio signalaccording to the instructions associated with block 708.

In some embodiments, negative rank scaling associated with block 708involves computing an instantaneous frequency (F_(in)) over the analysisband (e.g., the frequency range of the input audio signal wherehigh-frequency speech is to be analyzed, e.g., the frequency rangeanalyzed according to the instructions of block 704) by comparing thephase shift across successive fast Fourier transform (FFT) segments.Preserving phase, these components are reproduced at lower frequencies(F_(out)) using sine wave resynthesis, in these embodiments, in whichoutput frequency is a reciprocal of input frequency as specified by thefollowing formulae:

$\begin{matrix}{F_{out} = {{- \left( {\frac{F_{in}^{- p}}{CompRange} \times {outputBW}} \right)} + {baseline}}} & \left\{ {{Eq}.\mspace{14mu} 1} \right\}\end{matrix}$

Where, “p” is the compression exponent, “CompRange” is the range of thecompressed version of the input audio signal, e.g., the range of theinaudible region 401 of the input audio signal 403 in FIG. 4 expressedin terms of log frequency (e.g., scaled by the negative exponent p),“outputBW” is the bandwidth (range) of the output audio signal, and“baseline” shifts the intercept and moves the function from quadrant IVto quadrant I of the Cartesian plane. The net effect is that thereciprocal function (an example of a negative rank function) is scaled(e.g., compressed) so that the minimum input frequency (minF_(in))becomes the maximum output frequency (maxF_(out)) and the maximum inputfrequency (maxF_(in)) becomes the minimum output frequency (minF_(out)):

$\begin{matrix}{{CompRange} = {{maxF}_{in}^{- p} - {minF}_{in}^{- p}}} & \left\{ {{Eq}.\mspace{14mu} 2} \right\} \\{{outputBW} = {{maxF}_{out} - {minF}_{out}}} & \left\{ {{Eq}.\mspace{14mu} 3} \right\} \\{{baseline} = {\left( {\frac{{minF}_{in}^{- p}}{CompRange} \times {outputBw}} \right) + {maxF}_{out}}} & \left\{ {{Eq}.\mspace{14mu} 4} \right\}\end{matrix}$

In other words, in some embodiments, the data processing device systemis configured, according to the program instructions associated withblock 708, at least to generate the output audio signal at least byfrequency inverting and compressing at least a portion (e.g., one ormore frequency ranges, one or more time segments, or both) of the inputaudio signal. In this regard, the negative rank scaling includes aninversion of an ordering of frequencies present in the at least theportion of the input audio signal.

In some embodiments of the above-discussed negative rank scaling ofblock 708, the parameters used for such negative rank scaling werechosen following several small-scale pilot studies using normal-hearinglisteners who each discriminated /s/ and /∫/ across almost 1200 trials.In these embodiments, the analysis band was intentionally limited tofrequencies where the majority of frication energy is produced. At thelow end of the range, minF_(in) was set to 2756 Hz (a value thatrespects the FFT bin spacing). After some experimentation with highervalues, the value chosen for maxF_(in) was 7924 Hz. This experimentationwas done in conjunction with setting the value for minF_(out), which wasultimately chosen to be 200 Hz. maxF_(out) is a variable parameter thatis set to equal the maximum frequency for which aided audibility can beprovided for the individual patient. Likewise, the compression exponentp is intended to be a parameter that is chosen for the individualpatient. It is expected that values of p ranging from 0.25 to 2.5 shouldbe sufficient for most patients, which will also depend on maxF_(out).For example, during pilot studies in which maxF_(out) was 1500 Hz,p=1.75 yielded the best performance not only for identification of /s/and /∫/, but also for other consonants. (It should be noted, however,that the invention is not limited to the details of the embodiments(including the above discussed parameters) described above with respectto block 708, which are referred to for purposes of illustration only.Further, one or more aspects of these embodiments may be incorporatedinto other embodiments of the present invention.)

According to some embodiments of the present invention, the negativerank ordering or scaling of block 708 involves an inversion of anordering of frequency segments or ranges from input-to-output, and notnecessarily an inversion of an ordering of the individual frequencieswithin each segment. For a simple example, assume that a high-frequencyregion of the input audio signal 702 includes, from lowest-to-highestfrequency, frequency sub-ranges or frequency sub-segments A and B.Frequency segment A, may include, from lowest-to-highest frequency,individual frequencies A1 and A2, and frequency segment B may include,from lowest-to-highest frequency, individual frequencies B1 and B2. Uponnegative rank ordering or scaling of such an input audio signal, thelow-frequency region of the output audio signal output from block 708may include, according to some embodiments of the present invention,from lowest-to-highest frequency, the frequency segments B and A, ormore specifically, may include the following sequence of individualfrequencies, from lowest frequency to highest frequency: B1, B2, A1, andA2.

According to some embodiments of the present invention, an additionalspeech feature detector (e.g., in addition to the speech featuredetector of block 704) may be implemented as part of the method 700. Insome embodiments, this additional speech feature detector takes the formof block 710, which further classifies /s/ (high-frequency) from /∫/(mid-frequency), for example.

Accordingly, when /s/ is detected (e.g., block 710), it may bebeneficial to provide the user with an additional cue (e.g., block 712)to further distinguish /s/ from /∫/. This additional cue, according tosome embodiments, is the providing of a differential gain (e.g., block712) to help further segregate the two signals of origin on the basis ofloudness. In other words, an additional perceptual cue may be provided(e.g., block 712) in the form of loudness (e.g., a differential gain)based on a phonemic classification of the speech (e.g., block 710). Sucha differential gain may be applied after a gain has been applied to theinput audio signal 702 by the filtering/conditioning circuitry 604 toamplify regions of frequency where the user is experiencing hearingloss. However, such a gain to frequency ranges where the user isexperiencing hearing loss need not be separately applied, and may beapplied in conjunction with the differential gain of block 712,according to some embodiments.

In some embodiments, the speech feature detector of block 710 mayinclude the data processing device system 510 determining whether thespectral balance of a portion or time segment of the input audio signalincludes a high-frequency tilt (e.g., exhibits higher energy at ahigh-frequency range as compared to a mid-frequency range), theportion/time segment having been identified according to theinstructions associated with block 704 to include useful high-frequencyspeech. The high-frequency tilt detected according to the programinstructions associated with block 710 facilitates the detection of /s/.However, it should be noted that any other type of speech featuredetector may be executed at block 710.

According to some embodiments, in response to determining that the inputaudio signal exhibits the high-frequency tilt (e.g., exhibits the higherenergy at the high-frequency range), the data processing device system510, according to the instructions associated with block 712, attenuatesa low-frequency range of the output audio signal, which was output fromthe negative rank ordering or scaling (e.g., output from block 708). Theattenuation of the low-frequency range of the output audio signal may,in some embodiments, be relative to another frequency range or anothertime segment of the output audio signal. The attenuated low-frequencyrange of the output audio signal may correspond to the high-frequencyrange of the input audio signal that is negative rank ordered or scaled(e.g., inverted) according to the instructions associated with block708. Stated differently, the attenuated low-frequency range of theoutput audio signal may correspond to the segment of the input audiosignal that is frequency-lowered or transposed by the negative rankordering or scaling performed according to the instructions of block708. In other words, in some embodiments, the attenuated low-frequencyrange of the output audio signal includes the low frequency 408 in FIG.4 and corresponds to the segment of the input audio signal including thehigh frequency 406 in FIG. 4. This attenuating of the low-frequencyrange of the output audio signal (e.g., output from block 708) may be toa greater extent than any attenuating of the output audio signal (e.g.,output from block 708) at a frequency range other than the low-frequencyrange of the output audio signal (e.g., output from block 708). Forexample, while the low-frequency range of the output audio signal (e.g.,including low frequency 408 in FIG. 4) is attenuated, the otherfrequencies of the output audio signal (e.g., including higher frequency407 in FIG. 4) may not be attenuated, or at least may be attenuated to alesser extent. In other words, the attenuation occurring according tothe program instructions associated with block 712 may be a relativeattenuation of the low-frequency range of the output audio signal ascompared to another frequency range of the output audio signal. However,in some embodiments, the attenuation applied according to the programinstructions of block 712 is an attenuation of the entire high frequencyrange of the input audio signal 702 that becomes frequency lowered bythe negative rank ordering or scaling of block 708. In this regard,although /s/ and /∫/ have a peak energy at different frequencies, theyare broadband and so have energy at overlapping frequencies in the inputaudio signal (therefore, in the output audio signal output from block508 also). (See, e.g., FIG. 11( a) and FIG. 11( b), which are discussedin more detail below. In FIG. 11( a) and FIG. 11( b), it can be noticedhow the spectral content after lowering (e.g., block 708) overlaps (asit does before lowering), but how the overall energy in the region ofgreatest overlap is less for /s/ (FIG. 11 a) than for /∫/ (FIG. 11 b).)In this regard, in some embodiments, the program instructions associatedwith block 712 add an addition perceptual cue to help the user orlistener to distinguish /s/ from /∫/.

While the above discussion of block 712 pertains to attenuation of theoutput audio signal, it should be noted that the present invention alsoincludes applying a gain (or less of a gain in some embodiments) to atleast a portion or frequency range of the output audio signal (e.g.,output from block 708) at block 712, for example, instead of or inaddition to attenuating a portion or frequency range of the output audiosignal (e.g., output from block 708). For example, in some embodiments,the attenuation of block 712 is instead a differential gain, such thatprogram instructions associated with block 712 cause or configure thedata processing device system 510 to apply a gain to the low-frequencyrange of the output audio signal (e.g., including frequency 408 in FIG.4) that is to a different extent than a gain applied to another or anyother frequency range of the output audio signal (e.g., includingfrequency 407 in FIG. 4). For instance, the data processing devicesystem 510 may apply less of a gain to the low-frequency range of theoutput audio signal than that applied to the other frequencies of theoutput audio signal. Alternatively, the data processing device system510 may apply no gain or an attenuation to the low-frequency range ofthe output audio signal according to the instructions of block 712,while applying a gain to the other frequencies of the output audiosignal. In this regard, it can be seen that the present invention is notlimited to any particular combination of gains, attenuations, or one ormore gains and one or more attenuations applied according to the programinstructions associated with block 712.

In this regard, in some embodiments, the data processing device system510 may be configured by program instructions associated with block 712to cause, by way of at least a gain, an attenuation, or both a gain andan attenuation, and in response to determining that the input audiosignal exhibits the higher energy at the high-frequency range at block710, a low-frequency range of the output audio signal to be relativelyde-emphasized or emphasized as compared to another frequency range oranother time segment of the output audio signal in order to provide auser or listener with an additional perceptual cue to distinguishsimilar sounds. The low-frequency range of the output audio signal maycorrespond, prior to the negative rank ordering or scaling of block 708(which may be a frequency inversion, according to some embodiments) ofthe input audio signal, to the high-frequency range of the input audiosignal.

Further, although attenuation, gain, or both, has been discussed asbeing applied according to the instructions associated with block 712 tothe audio signal output from block 708, it should be appreciated thatsuch attenuation, gain, or both may instead be applied to the inputaudio signal (e.g., just upstream of block 708) prior to performingnegative rank ordering or scaling according to the instructionsassociated with block 708. For example, blocks 710 and 712 couldselectively de-emphasize/emphasize the high-frequency range (e.g.,including the frequency 406 in FIG. 4) of the input audio signal (e.g.,at a point exiting block 704 in FIG. 7), such that thehigh-frequency-de-emphasized (or emphasized) input audio signal ispassed to block 708 for negative rank ordering or scaling. In thisregard, it may be said that, in response to determining that the inputaudio signal contains a particular sound (e.g., exhibits higher energyat the high-frequency range (e.g., pursuant to block 710), such as /s/),an output audio signal is generated to include a perceptual cue (e.g.,pursuant to block 708) to distinguish the particular sound from asimilar sound (e.g., having overlapping frequencies with the particularsound, such as /s/ and /∫/) at least by applying a differential gain, adifferential attenuation, gain, an attenuation, or a combination of oneor more gains and attenuations to at least a portion or frequency rangeof the input audio signal in order to relatively de-emphasize oremphasize the high-frequency range of the input audio signal. If adifferential gain or a differential attenuation is applied to the inputaudio signal in this regard, the gain or attenuation applied to thehigh-frequency range of the input audio signal (e.g., including thefrequency 406 in FIG. 4) is to a different extent than any gain orattenuation applied to the input audio signal at a frequency range orall other frequencies (e.g., including frequency 410 in FIG. 4) otherthan the high-frequency range of the input audio signal.

In consideration of the selective nature of thede-emphasizing/emphasizing process of blocks 710 and 712, it should benoted that if the input audio signal 702 is considered an input audiosignal stream, block 712 may add the perceptual cue only when the speechfeature detector of block 710 detects its target sound or phoneme (e.g.,/s/).

In some embodiments where the speech feature detector of block 710detects high frequency tilt in order to detect a target sound orphoneme, in response to the data processing device system 510identifying, according to the program instructions associated with block710, that a first time segment of the input audio signal stream exhibitshigher energy at a high-frequency range as compared to a mid-frequencyrange (e.g., the target sound or phoneme has been detected), the dataprocessing device system 510 may cause, by way of at least a gain, anattenuation, or both a gain and an attenuation according to programinstructions associated with block 712, a low-frequency range of a firstportion or time segment of the output audio signal stream to beemphasized or de-emphasized as compared to another frequency range ofthe first portion or time segment of the output audio signal stream oras compared to another time segment of the output audio signal stream.In some embodiments, the low-frequency range of the first portion ortime segment of the output audio signal stream corresponds, prior to thenegative rank ordering or scaling of block 708 (which may be aninverting) of the first portion of time segment of the input audiosignal stream, to the high-frequency range of the first portion or timesegment of the input audio signal stream. Such emphasizing orde-emphasizing may add a perceptual cue to further distinguish thedetected target sound or phoneme (e.g., block 710) from a sound that issimilar (e.g., shares similar frequency characteristics so as to betypically confused by a listener) to the detected sound.

On the other hand, in some embodiments, if the data processing devicesystem 510 identifies, according to the program instructions associatedwith block 710, that a different time segment of the input audio signalstream exhibits higher energy at the mid-frequency range as compared tothe high-frequency range (e.g., the target sound or phoneme has not beendetected), the data processing device system 510 does not causeemphasizing or de-emphasizing according to block 712 of thehigh-frequency range of the input audio signal present in thelow-frequency range of the output audio signal. Consequently, in thiscase, the data processing device system 510 does not apply, according tosome embodiments of the program instructions associated with block 712,a differential gain, a differential attenuation, a gain, an attenuation,or a combination of one or more gains and attenuations, to at least aportion or frequency range of the different time segment of the inputaudio signal or a portion or time segment of the output audio signalcorresponding to the different time segment in order to relativelyemphasize or de-emphasize the high-frequency range of the input audiosignal, according to some embodiments. In other words, the perceptualcue of block 712 is not added in this case when the target sound orphoneme is not detected. In this regard, according to some embodiments,in response to determining that the input audio signal 702 does notcontain a target sound or phoneme (e.g., does not exhibit thehigh-frequency tilt) at block 710, the data processing device system 510does not perform the cue adding (e.g., differential gain) of block 712of the low-frequency range of the output of the negative rank orderingor scaling block 708. See, e.g., block 714.

The sound detection and cue adding processes of blocks 710 and 712provide an additional cue to the user for distinguishing between signalsthat are lowered and exist within similar frequency regions.Consequently, the sound detection and cue adding processes of blocks 710and 712 may be active at all times (e.g., constantly analyzing the inputaudio signal to determine whether a target sound or phoneme exists andwhether the cue-adding of block 712 should be applied). In someembodiments, such cue adding of block 712 is to be distinguished fromapplications of differential gain that merely make sounds in the regionsof greater hearing loss louder than the rest of the signal (such adifferential gain may be applied by the filtering/conditioning circuitry604). In contrast to such a differential gain, the differential gain ofblock 712 adds a perceptual cue to distinguish similar sounds and may beapplied after the differential gain that makes sounds in the regions ofgreater hearing loss louder than the rest of the signal. In this regard,the differential gain of block 712 that adds the perceptual cue is beingapplied independently or regardless of frequency regions where hearingloss is occurring for the user. Further in this regard, although theabove discussion of blocks 710 and 712 focused on facilitatingdistinguishing the phonemes /s/ and /∫/, it should be noted that blocks710 and 712 may also be adapted to facilitate distinguishing othersimilar phonemes, according to some embodiments of the presentinvention.

Although the determination of whether a target sound or phoneme existsaccording to the instructions associated with block 710 has beendescribed as applying to the input audio signal from blocks 702, 704,the present invention is not limited to this arrangement. In someembodiments, block 710 operates on the output audio signal output fromblock 708. In at least some of these embodiments, the programinstructions associated with block 710 are instead configured todetermine whether a target sound or phoneme (e.g., by way of alow-frequency tilt) exists in the output audio signal output from block708. If so, the low-frequency portion or range of the output audiosignal may be emphasized or de-emphasized according to the instructionsassociated with block 712 as previously discussed. If not, theemphasizing or de-emphasizing performed according to the instructionsassociated with block 712 is not executed, as illustrated by block 714.

As to some of the reasoning associated with performing the differentialgain (which may include an attenuation) according to the instructionsassociated with block 712, it is noted that the relative level of theentire frequency-lowered segment according to the negative rank orderingor scaling of block 708 depends on the spectral balance of the inputaudio signal. An intent is to enhance the perceptual dissimilarity ofspeech sounds with frication that is produced toward the front of themouth, which creates a peak of energy in the high frequencies (e.g.,/s/) from speech sounds with frication that is produced further back inmouth, which creates a peak of energy in the mid frequencies (e.g.,/∫/). An empirical examination of /s/ and /∫/ recordings in threevowel-consonant-vowel contexts (/a/, /i/, and /u/) from three adult maleand three adult female talkers was used to optimize, according to someembodiments, the analysis at block 710 by the data processing devicesystem 510 based on spectral balance. In this regard, in someembodiments, the data processing device system 510 is configured tocompare the band-pass filtered energy of the input audio signal segmentfrom 2500-4500 Hz to the high-pass filtered energy above 4500 Hz.

In some of these embodiments, if the energy of the input audio signalsegment at block 710 from 2500-4500 Hz is greater than the energy above4500 Hz, at least the frequency-lowered segment of the output audiosignal from block 708 is passed through to the next stage of processing(e.g., at block 714 to the sound producing device system 610 in FIG. 6)without differential gain (e.g., attenuation) of the frequency-loweredsegment according to block 712.

On the other hand, according to some embodiments, if the energy of theinput segment above 4500 Hz is greater than the energy from 2500-4500Hz, the frequency-lowered segment is subject to differential gain (e.g.,attenuated) at block 712 before being passed through to the next stageof processing (e.g., to the sound producing device system 610 in FIG.6). In some embodiments, block 712 may involve an attenuation of 4-9 dB.In this regard, it should be noted that a small group of pilot studieswith a larger difference (10 dB) and smaller difference (3 dB), did notyield comparable outcomes as a 6 dB difference. It should also be notedthat, although the above discussion refers to the particular range of2500-4500 Hz for block 710 and 4-9 dB of attenuation for block 712 insome embodiments, the present invention is not limited to theseparticular ranges, and different applications may be better suited forother ranges. The ranges provided herein are merely for purposes ofillustration and to provide examples that may be suitable for someparticular applications of many applications to which the presentinvention may be applied.

In this regard, it is noted that in some embodiments, at least fourparameters implemented in the method 700 may be adjustable toaccommodate differences between individuals:

-   -   (1) the upper frequency limit of the output, maxF_(out) (e.g.,        block 708);    -   (2) the compression exponent, p (e.g., block 708);    -   (3) the overall level of the frequency-lowered segments (e.g.,        blocks 712 and 714) relative to the un-lowered segments (e.g.        block 706); and    -   (4) the relative level difference of the added level cue (e.g.,        block 712).

The upper frequency limit of the output, maxF_(out) (parameter (1),above), in some embodiments, is set equal to the maximum audiblefrequency based on the individual's hearing loss. That is, the bandwidthof the output may be set equal to the bandwidth of the audible spectrum(while this seems logical, it is not typically a consideration of manyother methods). FIG. 8 shows how maxF_(out) may be set, according tosome embodiments, for hearing losses in which audibility drops off at1500, 2000, 2500, and 3000 Hz. As can be seen in FIG. 8, increasingmaxF_(out) shifts the overall function vertically toward the perceptualspace for /∫/, but will expand it since the acoustic differences betweenthe output for /s/ and /∫/ will be greater. How this shift will affectperception will depend on the individual. Therefore, to maximize thediscriminability of /s/ and /∫/, the compression exponent, p (parameter(2), above), may be variable to accommodate differences in perceptionbetween individuals. An assumption is that improvement in discriminationfor this sound contrast will also improve discrimination of other soundcontrasts.

In general, a higher value (i.e., more compression) should increase theperception of /s/, while a lower value (i.e., less compression) shouldincrease the perception of /∫/. FIG. 9 shows the I/O functions for p=0.5to p=2.5. While, the functions in FIG. 9 appear to be very compressivewhen plotted on a linear Hertz scale, one must consider that filteringin the inner ear is logarithmic. FIG. 10 plots the same functions on apsychophysical scale (the ERB (equivalent rectangular bandwidth)) inwhich the numbers correspond to independent auditory filter bands (See,e.g., Glasberg, B. R., and Moore, B. C. J. (1990), “Derivation ofauditory filter shapes from notched-noise data,” Hear Res 47, 103-138).When plotted this way, the functions are only moderately nonlinear, andin fact, are expansive (slope <−1.0), rather than compressive. Thisoccurs because the analysis band, in these embodiments, was restrictedto 2756-7924 Hz, or about 9.5 ERB. In contrast, even with maxF_(out) setas low as 1500 Hz, the output band is at least 13 ERB wide. That is,spectral resolution (the ability to distinguish peaks close together infrequency) of the lowered signal is greater than that of the originalinput signal.

Other adjustable parameters of the method 700 are the overall level ofthe frequency-lowered segments relative to the un-lowered segments(parameter (3), above) and the relative level difference of the addedintensity cue (parameter (4), above). The overall level may simply beadjusted to balance perceptual salience (i.e., the ability to perceivethe cue) and distractibility (i.e., complaints of the cue being ‘toonoisy’ or ‘too unnatural’). The purpose of including relative leveldifference as an adjustable parameter is to account for the fact thathearing aids will usually compress output level to fit the wide dynamicrange of input level into the narrower dynamic range of the hearing lossso that lower level sounds receive greater gain than higher levelsounds. The relative intensity cue might be adjusted automatically toaccount for this reduction in dynamic range (i.e., the size of the levelcue) or might be adjusted based on a brief perceptual testing thatattempts to find the parameters that maximize /s/−/∫/ discrimination.

In some embodiments, regarding parameter (3), above, the output of block714 was attenuated, relative to the output of block 706, by 2 to 4 dB(from its original bandpass input level), whereas the output of block712 was another 8 to 10 dB lower. That is, both the output of block 712and the output of block 714 was attenuated, in these embodiments,relative to their original bandpass level present in the input audiosignal 702. However, in these embodiments, the output of block 712 wasattenuated more than the output of block 714. Subsequent to thisattenuation, hearing aid gain was then applied to both outputs toaccommodate individual hearing loss, according to these embodiments. Theperceptual reason for this is that even for normal-hearing listeners alow-frequency sound will be perceived as louder than a high-frequencysound of the exact same intensity. So, if the overall intensity of thelowered /s/ and /∫/ (and other high-frequency speech sounds) are keptthe same, they will sound loud relative to how a listener is used tohearing them. To help keep the perceptual balance, these embodimentssimply turn the volume of the lowered speech down. This phenomenon willvary between listeners, especially those who have never heard thesehigh-frequency sounds before and who have no basis for judging how loudthey should sound. In this regard, listeners might want them louder sothat they are better able to perceive them.

First Comparative Examples

FIG. 11 compares spectrograms of the vowel-consonant-vowels (“VCVs”)/asa/ and /a∫a/ after negative rank ordering or scaling processingaccording to the method 700, with maxF_(out)=1500 Hz, p=1.75, and levelcue (e.g., attenuation according to block 712) =6 dB, as shown in FIG.11( a) and FIG. 11( b), respectively, to processing with a simulation ofa conventional linear frequency compression (“LFC”) technique as shownin FIG. 11( c) and FIG. 11( d). While /∫/ is grossly similar with thetwo methods (FIG. 11( b) and FIG. 11( d)), /s/ shows a more drasticdifference. With negative rank ordering or scaling of frequency (e.g.,block 708) and application of differential gain (e.g., block 712), theenergy for /s/ (FIG. 11( a)) is less intense and is concentrated towardthe lowest frequencies, which makes it rather distinct from /∫/ (FIG.11( b)). In contrast, with linear frequency compression, the energy for/s/ (FIG. 11( c)) is concentrated toward the highest end of the outputrange and is less distinct from /∫/ (FIG. 11( d)). Furthermore, theenergy for /s/ in FIG. 11( c) is in the region most listenersperceptually categorize as /∫/, which should make it more difficult torelearn when acclimatizing to the new speech code.

Second Comparative Examples

A basis of comparison for evaluating the performance of the method 700in FIG. 7 are a series experiments reported by Shames and Alexander(Shames, Y. A., and Alexander, J. M. (2011), “Novel dynamic frequencylowering techniques for precipitous hearing loss,” American AuditorySociety (Abstract)) in which a variety of positive rank scaling methodsof frequency lowering, including a 1500-Hz low-pass filtered condition,were tested on 20 normal-hearing listeners each who identified 240 VCVs(20 consonants spoken by four talkers in three vowel contexts) and 144nonsense syllables differing only in the medial vowel (12 vowels spokenby 12 talkers). Frequency lowering for all conditions was dependent onthe spectral balance of the input, using the method of block 704. Thefrequency I/O functions for the methods reported on are shown in FIG.12. Each was tested with and without an added level cue (5 dB) fromblock 710. In general, overall performance was better with the addedlevel cue (block 710) regardless of frequency-lowering method, so theseare the only results reported. The LFC line in FIG. 12 is the frequencymapping representing the linear frequency compression technique (LFC).The NFC line represents nonlinear frequency compression (NFC) using theequation described by Simpson et al. (Simpson, A., Hersbach, A. A., &McDermott, H. J. (2005), “Improvements in speech perception with anexperimental nonlinear frequency compression hearing device,” Int J Aud44, 281-92). The TFC (truncated frequency compression) line representsthe same, except with an analysis band that was truncated to 2756-7924Hz, which the same range as shown in FIG. 9 for one embodiment ofnegative rank ordering or scaling of frequency. Finally, the EFC(expanded frequency compression) line represents an alternative mappingin which high-frequency inputs were assigned a relatively expandedfrequency space in the output. Results for each are shown in FIGS.13-18.

The top part of each of FIGS. 13-18 shows the stimulus-response matrixwhere the rows represent the consonant stimuli that were presented andwhere the columns represent the responses aggregated over 20 listeners.Thus, numbers along the diagonal are correct responses and numbers alongthe off-diagonal are incorrect responses. As can be seen from Table 1 inFIG. 13, severely band-limited speech results in a high number ofconfusions of /∫/ for /s/. Other notable confusions within the contextof the current set of experiments are /t/ for /t∫/ and /t/ for /k/. Thebottom part of each of FIGS. 13-18 shows the d-prime (d′) for eachconsonant overall and for each pair of confusions. The advantage of d′is that it takes into account false alarms as well as hits (Macmillan,N. A. and Creelman, C. D. (2005), “Detection theory: A user's guide,”2nd Ed. (Erlbaum, N.J. )). For example, if stimulus A is alwaysperceived correctly, but stimulus B is also always perceived as stimulusA, then the listener is not sensitive to the contrast (d′=0), despitebeing 100% correct for stimulus A. Thus, d′=0.2 for the /s/−/∫/ contrastin Table 1 of FIG. 13 reflects the high number of confusions of /∫/ for/s/.

Table 2 of FIG. 14 shows the results for a simulation of linearfrequency compression. Interestingly, while there was a doubling in thenumber correct responses for /∫/, this came at the expense of a triplingin the number of confusions of /∫/ for /s/, hence there was noimprovement for d′ for this contrast. Similarly, while the number ofconfusions of /t/ for /k/ was reduced, so was the number of correctresponses for /t/, thus there was no improvement in d′. Finally, therewas an overall in increase in the number of confusions of /t∫/ for both/s/ and /∫/.

Table 3 of FIG. 15 shows the results for nonlinear frequencycompression, which fared a little better than linear frequencycompression. This was especially true for the number of correct /s/ and/∫/ responses, which increased without much of an increase in the numberof /s/−/∫/ confusions. Also, relative to linear frequency compression,there was a modest increase in the number of correct /t/ and /k/responses with a similar number of confusions between the two methods.Finally, unlike linear frequency compression, there were a low number ofconfusions of /t∫/ for /s/ and /∫/.

Table 4 of FIG. 16 shows the results for truncated (nonlinear) frequencycompression. Relative to the other frequency-lowering methods, the mostnotable pattern is the significant increase in the number of /∫/responses for both /s/ and /∫/ stimuli.

Table 5 of FIG. 17 shows the results for expanded (nonlinear) frequencycompression. While perception of /s/ and /∫/ was more balanced than theprevious experiments, overall percent correct with this method waslowest of all. In addition, compared to the other frequency loweringmethods, there were a significant number of /t/ confusions for /t∫/ andonly ⅓ to ¼ the number of correct /t∫/ responses.

Table 6 of FIG. 18 shows the results for the method 700 of FIG. 7, alsoreferred to as inverse frequency compression (“IFC”), according to someembodiments. The first aspect to note is that overall percent correct isthe highest of all other methods tested. In addition, d′ for the/s/−/∫/, /t/−/k/, and /∫/−/t∫/ contrasts were the highest of all testedmethods, among others. For the /s/−/∫/ contrast, the number of correctresponses are balanced (i.e., unbiased) with a relatively modest numberof confusions between the two and with a minimal number of confusionswith /t∫/. If the overall d′ for IFC for each of the consonants iscompared to LFC, not only is there improvement (here, defined as a d′difference ≧0.2) for /s/ and /∫/, but also for other phonemes, including/t/, /k/, /z/, /d₃/, /t∫/, and /j/. Compared to low-pass filtering,improvements with IFC are seen for half of the consonants: /k/, /Θ/,/s/, /∫/, /v/, /j/, /t∫/, /r/, /w/, and /y/.

Finally, because each of the tested methods implemented frequencylowering only when there was a dominance of high-frequency energy andbecause vowels have a dominance of low frequency energy, none of theconditions tested differed significantly in overall vowelidentification.

It is to be understood that the above-described embodiments are merelyillustrative of the present invention and that many variations of theabove-described embodiments can be devised by one skilled in the artwithout departing from the scope of the invention. It is thereforeintended that all such variations be included within the invention andthe scope of the following claims and their equivalents.

1. (canceled)
 2. A sound processing device system configured to assist ahearing-impaired human listener recognize sounds, the sound processingdevice system comprising: a memory device system; and a data processingdevice system communicatively connected to the memory device system, thedata processing device system configured by a program stored in thememory device system at least to: receive an input audio signal; andgenerate an output audio signal at least by transposing and causing anegative rank ordering of frequency of at least a portion of the inputaudio signal.
 3. The sound processing device system of claim 2, whereinthe data processing device system is configured by the program at leastto generate an output audio signal at least by transposing and causing anegative rank ordering of a high-frequency portion of the input audiosignal, the high frequency portion of the input audio signal becoming alow-frequency portion of the output audio signal.
 4. The soundprocessing device system of claim 3, wherein the low-frequency portionof the output audio signal represents an inverted ordering offrequencies present in the high-frequency portion of the input audiosignal.
 5. The sound processing device system of claim 2, wherein thenegative rank ordering includes an inversion of an ordering offrequencies present in the at least the portion of the input audiosignal.
 6. The sound processing device system of claim 2, furthercomprising: a sound receiving device system communicatively connected tothe data processing device system and configured to receive sound andgenerate the input audio signal; and a sound producing device systemcommunicatively connected to the data processing device system andconfigured to produce sound based upon the output audio signal.
 7. Thesound processing device system of claim 2, wherein the negative rankordering includes frequency inverting and compressing the at least theportion of the input audio signal.
 8. The sound processing device systemof claim 2, wherein the input audio signal is a first portion of aninput audio signal stream, wherein the output audio signal is a firstportion of an output audio signal stream, and wherein the dataprocessing device system is configured by the program at least to:identify a speech pattern present in the first portion of the inputaudio signal stream; generate, in response to the speech pattern beingidentified as present in the first portion of the input audio signalstream, the first portion of the output audio signal stream at least byinverting a frequency relationship of at least part of the first portionof the input audio signal stream; identify that the speech pattern isnot present in a second portion of the input audio signal stream that isother than the first portion of the input audio signal stream; andgenerate, in response to identifying that the speech pattern is notpresent in the second portion of the input audio signal stream, a secondportion of the output audio signal stream without inverting thefrequency relationship of at least part of the second portion of theinput audio signal stream, the second portion of the output audio signalstream being other than the first portion of the output audio signalstream.
 9. The sound processing device system of claim 2, wherein thedata processing device system is configured by the program at least to:determine whether or not the input audio signal exhibits higher energyat a high-frequency range than at a mid-frequency range of the inputaudio signal; and cause, by way of at least a gain, an attenuation, orboth a gain and an attenuation, and in response to determining that theinput audio signal exhibits the higher energy at the high-frequencyrange, a low-frequency range of the output audio signal to be relativelyemphasized or de-emphasized as compared to another frequency range oranother time segment of the output audio signal to generate a perceptualcue to facilitate distinguishing of similar sounds, the low-frequencyrange of the output audio signal corresponding, prior to the transposingand negative rank ordering of the input audio signal, to thehigh-frequency range of the input audio signal.
 10. The sound processingdevice system of claim 2, wherein the data processing device system isconfigured by the program at least to: determine whether or not theoutput audio signal exhibits higher energy at a low-frequency range thanat a mid-frequency range of the output audio signal; and cause, by wayof at least a gain, an attenuation, or both a gain and an attenuation,and in response to determining that the input audio signal exhibits thehigher energy at the high-frequency range, the low-frequency range ofthe output audio signal to be relatively emphasized or de-emphasized ascompared to another frequency range or another time segment of theoutput audio signal to generate a perceptual cue to facilitatedistinguishing of similar sounds, the low-frequency range of the outputaudio signal corresponding, prior to the transposing and negative rankordering of the input audio signal, to the high-frequency range of theinput audio signal.
 11. The sound processing device system of claim 8,wherein the data processing device system is configured by the programat least to: identify that the first portion of the input audio signalstream exhibits higher energy at a high-frequency range as compared to amid-frequency range of the first portion of the input audio signalstream; and cause, by way of at least a gain, an attenuation, or both again and an attenuation, and in response to identifying that the firstportion of the input audio signal stream exhibits the higher energy atthe high-frequency range, a low-frequency range of the first portion ofthe output audio signal stream to be relatively emphasized orde-emphasized as compared to another frequency range of the firstportion of the output audio signal stream or another time segment of theoutput audio signal stream to generate a perceptual cue to facilitatedistinguishing of similar sounds, the low-frequency range of the firstportion of the output audio signal stream corresponding, prior to theinverting the frequency relationship of the first portion of the inputaudio signal stream, to the high-frequency range of the first portion ofthe input audio signal stream.
 12. The sound processing device system ofclaim 11, wherein the data processing device system is configured by theprogram at least to: identify a speech pattern present in a thirdportion of the input audio signal stream that is other than the firstportion of the input audio signal stream and the second portion of theinput audio signal stream; generate, in response to the speech patternbeing identified as present in the third portion of the input audiosignal stream, a third portion of the output audio signal stream atleast by inverting a frequency relationship of the third portion of theinput audio signal stream, the third portion of the output audio signalstream being other than the first portion of the output audio signalstream and the second portion of the output audio signal stream;identify that the third portion of the input audio signal streamexhibits higher energy at a mid-frequency range as compared to ahigh-frequency range of the third portion of the input audio signalstream; and output the third portion of the output audio signal streamwithout causing, by way of at least a gain, an attenuation, or both again and an attenuation, a low-frequency range of the third portion ofthe output audio signal stream to be relatively emphasized orde-emphasized as compared to another frequency range of the thirdportion of the output audio signal stream or another time segment of theoutput audio signal stream, the low-frequency range of the third portionof the output audio signal stream corresponding, prior to the invertingthe frequency relationship of the third portion of the input audiosignal stream, to the high-frequency range of the third portion of theinput audio signal stream.
 13. The sound processing device system ofclaim 8, wherein the speech pattern is frication.
 14. A sound processingdevice system configured to assist a hearing-impaired human listenerrecognize sounds, the sound processing device system comprising: amemory device system; and a data processing device systemcommunicatively connected to the memory device system, the dataprocessing device system configured by a program stored in the memorydevice system at least to: receive an input audio signal; generate anoutput audio signal based at least upon a processing of the input audiosignal; and determine that (a) the input audio signal exhibits higherenergy at a high-frequency range as compared to a mid-frequency range ofthe input audio signal, or (b) the output audio signal exhibits higherenergy at a low-frequency range as compared to a mid-frequency range ofthe output audio signal, wherein, in response to determining (a) or (b),the data processing device system is configured by the program at leastto cause the output audio signal to include a perceptual cue at least byincluding an emphasis or a de-emphasis of the low-frequency range of theoutput audio signal as compared to another frequency range or anothertime segment of the output audio signal at least by an application of again, an attenuation, or both a gain and an attenuation, the perceptualcue being caused to be included regardless of frequency regions wherehearing loss is occurring for the hearing-impaired human listener. 15.The sound processing device system of claim 14, further comprising: asound receiving device system communicatively connected to the dataprocessing device system and configured to receive sound and generatethe input audio signal; and a sound producing device systemcommunicatively connected to the data processing device system andconfigured to produce sound based upon the output audio signal.
 16. Thesound processing device system of claim 14, wherein the processing ofthe input audio signal includes transposing and causing a negative rankordering of frequency of at least a portion of the input audio signal.17. The sound processing device system of claim 16, wherein the negativerank ordering includes an inversion of an ordering of frequenciespresent in the at least the portion of the input audio signal.
 18. Thesound processing device system of claim 16, wherein the processing ofthe input audio signal includes frequency inverting and compressing atleast the portion of the input audio signal.
 19. The sound processingdevice system of claim 14, wherein the processing of the input audiosignal includes transposing and causing a negative rank ordering of thehigh-frequency portion of the input audio signal, the high frequencyportion of the input audio signal becoming the low-frequency portion ofthe output audio signal.
 20. The sound processing device system of claim14, wherein the input audio signal is a first portion of an input audiosignal stream, wherein the output audio signal is a first portion of anoutput audio signal stream, and wherein the data processing devicesystem is configured by the program at least to: identify a speechpattern present in the first portion of the input audio signal stream;generate, in response to the speech pattern being identified as presentin the first portion of the input audio signal stream, the first portionof the output audio signal stream at least by transposing and causing anegative rank ordering of frequency of at least part of the firstportion of the input audio signal stream; identify that the speechpattern is not present in a second portion of the input audio signalstream that is other than the first portion of the input audio signalstream; and generate, in response to identifying that the speech patternis not present in the second portion of the input audio signal stream, asecond portion of the output audio signal stream without inverting afrequency relationship of at least part of the second portion of theinput audio signal stream, the second portion of the output audio signalstream being other than the first portion of the output audio signalstream.
 21. A hearing aid device comprising: a sound receiving devicesystem configured to receive sound and generate an input audio signal; asound producing device system configured to produce sound based upon anoutput audio signal; a memory device system; and a data processingdevice system communicatively connected to the memory device system, thesound receiving device system, and the sound producing device system,the data processing device system configured by a program stored in thememory device system at least to: receive the input audio signal;identify a speech pattern present in the input audio signal; generate,in response to the speech pattern being identified as present in theinput audio signal, the output audio signal at least by transposing andcausing a negative rank scaling of frequency of at least a portion ofthe input audio signal; identify that the input audio signal exhibitshigher energy at a high-frequency range as compared to a mid-frequencyrange of the input audio signal; and cause, by way of at least a gain,an attenuation, or both a gain and an attenuation, and in response todetermining that the input audio signal exhibits the higher energy atthe high-frequency range, a low-frequency range of the output audiosignal to be relatively emphasized or de-emphasized as compared toanother frequency range or another time segment of the output audiosignal to generate a perceptual cue to facilitate distinguishing ofsimilar sounds, the low-frequency range of the output audio signalcorresponding, prior to the transposing and causing the negative rankscaling of frequency of the input audio signal, to the high-frequencyrange of the input audio signal.